scholarly journals Variability of Alternaria Leaf Spot Resistance in Jerusalem Artichoke (Helianthus Tuberosus L.) Accessions Grown in a Humid Tropical Region

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 268 ◽  
Author(s):  
Viriyasuthee ◽  
Saksirirat ◽  
Saepaisan ◽  
Gleason ◽  
Jogloy
Keyword(s):  
Disease Severity ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Jerusalem Artichoke ◽  
Severity Index ◽  
Field Conditions ◽  
Helianthus Tuberosus ◽  
Disease Severity Index ◽  
Alternaria Leaf Spot ◽  
Progress Curve

Alternaria leaf spot is an emerging disease of Jerusalem artichoke (Helianthus tuberosus L.) in tropical regions. The lack of known resistant germplasm sources is an important constraint to development of Jerusalem artichoke varieties with resistance to Alternaria leaf spot. The objectives of this study were to identify variability of Jerusalem artichoke genotypes for resistance to Alternaria leaf spot under field conditions and to investigate the relationships among resistance characters, yield, and yield components for selection of resistant varieties. Ninety six accessions of Jerusalem artichoke were evaluated in replicated trials under field conditions in early rainy and late rainy seasons in Khon Kaen, Thailand during 2014. Parameters evaluated included disease incidence, disease score, disease severity index, area under disease progress curve of disease incidence, area under disease progress curve of disease severity index, number of tubers/plants, tuber size, and fresh tuber yield. The genotypes HEL 335, HEL 256, HEL 317, HEL 308, and JA 86 were identified as sources of leaf spot resistance in both seasons. These genotypes can be used as sources of leaf spot resistance for Jerusalem artichoke breeding programs. HEL 293 and HEL 246 showed susceptibility to leaf spot disease in both seasons and should be used as standard susceptible checks.

Resistance of standing milkvetch (Astragalus adsurgens) varieties to Embellisia astragali

2012 ◽  
Vol 63 (4) ◽  
pp. 351 ◽  
Author(s):  
B. H. Yu ◽  
Z. B. Nan ◽  
Y. Z. Li ◽  
H. L. Lin
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Agronomic Traits ◽  
Disease Incidence ◽  
Dry Weight ◽  
Severity Index ◽  
Field Conditions ◽  
Disease Severity Index ◽  
Greenhouse Experiments ◽  
Astragalus Adsurgens

Yellow stunt and root rot caused by Embellisia astragali are major factors contributing to declining yields of standing milkvetch (Astragalus adsurgens). The resistance of ten varieties of standing milkvetch to E. astragali was evaluated under laboratory, greenhouse, and field conditions. Seed germination/emergence, shoot and root length, plant dry weight, disease incidence, mortality, and disease severity index were monitored. The results show that Shanxi and Zhongsha No. 1 varieties had the best agronomic traits and lowest levels of disease in all experiments, while the varieties Neimeng and Ningxia had the highest susceptibility to disease. Germination/emergence differed significantly (P < 0.05) between varieties after inoculation, and compared with the control, germination/emergence of inoculated treatments of nine varieties decreased on average by 1.5% in laboratory experiments and by 4.1% in greenhouse experiments at 15 days after inoculation. Inoculation reduced shoot length by an average of 24.4% and 41.5% (P < 0.05) in laboratory and greenhouse experiments, respectively, in six of ten varieties. All varieties showed significantly (P < 0.05) lower plant dry weight following inoculation, with reductions ranging from 0.3 to 0.6 mg in the laboratory and from 82.6 to 149.4 mg in the greenhouse. Resistance to the pathogen was evaluated on the basis of disease incidence, a disease severity index (DSI), and mortality; varieties showing different resistance were grouped using cluster analysis. There were significant correlations between the results of laboratory and greenhouse experiments (r = 0.79; P < 0.01) and between greenhouse and field experiments (r = 0.83; P < 0.01) across all varieties. Multiple regression analysis between laboratory/greenhouse and field experiments on DSI suggested that screening in the laboratory/greenhouse could be an alternative method of rapidly estimating DSI under field conditions.

scholarly journals Effective Plant Ages for Screening for Field Resistance to Alternaria Leaf Spot (Caused by Alternaria spp.) under Natural Infection in Jerusalem artichoke (Helianthus tuberosus L.)

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 754 ◽  
Author(s):  
Wanalai Viriyasuthee ◽  
Suwita Saepaisan ◽  
Weerasak Saksirirat ◽  
Mark L. Gleason ◽  
Ruey Shyang Chen ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Natural Infection ◽  
Block Design ◽  
Jerusalem Artichoke ◽  
Plant Age ◽  
Growth Stages ◽  
Alternaria Leaf Spot ◽  
Progress Curve ◽  
The Impact

Host plant resistance has proven to be effective for controlling Alternaria leaf spot on Jerusalem artichoke (JA), but efficient screening techniques have not been developed yet. The objective of this study is to estimate the relationship between disease resistance parameters of JA as a function of plant age. Six JA varieties and three plant ages at the time of inoculation (20, 40 and 60 days after transplanting) (DAT) are evaluated in a factorial experiment in randomized complete block design (RCBD) with four replications. Disease incidence (DI) and severity (DS) are estimated, from which area under the disease progress curve (AUDPC) was calculated. Disease parameters are positively and significantly correlated for plant ages of 40 and 60 DAT. Based on our results, screening of JA at 40 DAT for resistance to Alternaria leaf spot is recommended. Knowledge of the impact of plant age on resistance to key diseases can help breeders to accelerate breeding programs so superior genotypes can be identified before reproductive growth stages.

Genetic analysis of Okra Yellow Vein Mosaic Virus disease resistance in wild relative of okra Abelmoschus angulosus Wall. ex Wight & Arn

2019 ◽  
Vol 17 (04) ◽  
pp. 346-351
Author(s):  
SamanthiKumari Wasala ◽  
Sumudu I. Senevirathne ◽  
Jayantha Bandara Senanayake ◽  
Anuradini Navoditha
Keyword(s):  
Disease Resistance ◽  
Mosaic Virus ◽  
Disease Severity ◽  
Virus Disease ◽  
Disease Incidence ◽  
Severity Index ◽  
Yellow Vein ◽  
Wild Relative ◽  
Yellow Vein Mosaic Virus ◽  
Progress Curve

AbstractWild relative of okra, Abelmoschus angulosus Wall. ex Wight &amp; Arn. was identified as a resistant germplasm for Okra Yellow Vein Mosaic Virus (OYVMV) which is the devastating disease for okra cultivation in Sri Lanka. The mode of resistance of OYVMV in A. angulosus was studied with the aim of tagging responsible genes for the disease resistance. Wide hybridization was performed between A. angulosus and highly virus susceptible A. esculentus variety, MI-7. Very poor seed setting was observed in F1 and F2 generations due to post zygotic abortion. Disease screening was carried out using F1 and F2:3 populations along with parents in the field under induced disease pressure. Disease severity index and area under disease progress curve were calculated to measure disease severity. Number of genes segregating for OYVMV disease resistance was calculated for the F2:3 generation. Modified Wright's formula was used to estimate the effective gene number and mode of inheritance by a quantitative method. A χ2 test was performed for qualitative analysis. Plants of A. angulosus were totally free of virus incidence while 100% disease incidence was observed in the variety MI-7. F2:3 population showed between and within progeny segregation for disease incidence. Results indicated that the disease susceptibility was dominant over resistance. χ2 analysis revealed that the segregation of disease severity was significantly fit to the gene model of 9:6:1 (χ2 = 0.1757 at P ≤ 0.05) suggesting the disease resistance in A. angulosus is governing by two recessive genes in an additive manner. Result was confirmed by the quantitative analysis.

scholarly journals Wilt and Root Diseases of Asclepias tuberosa L.

Plant Disease ◽  
1997 ◽  
Vol 81 (10) ◽  
pp. 1203-1205 ◽  
Author(s):  
L. Tsror (Lahkim) ◽  
M. Hazanovski ◽  
O. Erlich ◽  
N. Dagityar
Keyword(s):  
Disease Severity ◽  
Disease Incidence ◽  
Severity Index ◽  
Disease Severity Index ◽  
Dry Rot ◽  
First Report ◽  
Binucleate Rhizoctonia ◽  
Root Diseases ◽  
Tuberous Roots

Chlorosis and wilting, followed by weak flowering or death, have been occurring in Asclepias tuberosa plants grown in Israel. Roots have been rotted and tuberous roots have shown dark lesions, sometimes with sclerotia. A binucleate Rhizoctonia sp. was detected on 39% and Pythium intermedium on 23% of diseased samples. Other organisms were less prevalent. Wilting began 7 days after seedlings were inoculated with P. intermedium or the binucleate Rhizoctonia sp. or both, with disease incidence ranging from 25 to 65% and disease severity index ranging from 0.30 to 0.85 (scale of 0 to 3). Healthy tuberous roots inoculated with the binucleate Rhizoctonia sp. exhibited dry rot within 4 to 7 days, and irregular black sclerotia of the pathogen were present 2 weeks later. This is the first report of either a binucleate Rhizoctonia sp. or P. intermedium occurring in A. tuberosa.

scholarly journals Effect of Cultural and Biological Treatments in Managing Clubroot Disease of Cabbage in Sidhuwa, Nepal

2019 ◽  
Vol 7 (1) ◽  
pp. 96-101
Author(s):  
Ashish Ghimire ◽  
Sundarman Shrestha
Keyword(s):  
Disease Control ◽  
Disease Severity ◽  
Disease Incidence ◽  
Block Design ◽  
Combined Treatment ◽  
Severity Index ◽  
Disease Severity Index ◽  
Effective Microorganisms ◽  
Clubroot Disease ◽  
Biological Treatments

The Plasmodiophora brassicae Woronin is an important soil pathogen that attacks brassicaceae family of plants. The ability of pathogen to survive in soil for many years as a resting structure even in the absence of suitable host has increased its threat by making it more devastating. Lower effectiveness of treatments applied so far and failure to completely eradicate the disease once it enters the field has posed more problems. The study was conducted at a disease infected field in Sidhuwa, Dhankuta. It was focused on the effectiveness of different cultural and biological treatments against clubroot disease under field conditions. The treatments; lime, combination of lime and vermicompost, Effective Microorganisms (EM) solution and Trichoderma viride were arranged in Randomized Complete Block Design and replicated four times. The yield and yield attributing parameters and clubroot scale were recorded at the time of harvest. Values like Disease Incidence, Disease Severity Index and Disease Control Percentage were calculated based on clubroot scale value. The treatments showed no significant influence on vegetative parameters of the plants and on disease incidence. However, the combined treatment of lime and vermicompost was found to be most effective regarding disease severity and disease control i.e. the least Disease Severity Index (31.25%) and highest Disease Control Percentage (50.94%) compared to the control were obtained from the combined treatment of lime and vermicompost. Effective Microorganisms showed the highest disease severity. The combination of lime and vermicompost used as a treatment yielded highest marketable head weight (1.779 kg) and head diameter (19.90 cm). Int. J. Appl. Sci. Biotechnol. Vol 7(1): 96-101

scholarly journals Planting Technique Matters in Reducing Vinca Disease in Landscapes

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1004D-1004
Author(s):  
Yan Chen ◽  
Regina Bracy ◽  
Allen Owings
Keyword(s):  
Plant Growth ◽  
Disease Severity ◽  
Leaf Spot ◽  
Sandy Loam ◽  
Disease Incidence ◽  
Growth Index ◽  
Fertilization Rate ◽  
Negative Effects ◽  
Alternaria Leaf Spot ◽  
Quality Ratings

Annual vinca, Catharanthus roseus, is exceptionally adaptive to the summer heat and the sandy loam or clay soil in the southeastern region and provides season-long blooms once established in landscape plantings. A wide variety of colors, sizes, and applications are available for landscape use. However, diseases such as alternaria leaf spot and phytophthora leaf blight are prevalent in this region in vinca plantings. Effective disease control requires frequent fungicide application that is expensive and may pose negative effects on the environment. Proper planting techniques including date of planting, fertilization rate at planting, and variety selection may improve plant growth, reduce disease severity, and save landscape service business labor in disease management. Plants of three varieties: open-pollinated `Cooler Hot Rose', F1 hybrid `Titan Rose', and trailing variety `Mediterranean Lilac' were planted on 1 Apr. or 1 May in landscape plots. Plants were at the same growth stage at the time of planting and were fertilized with Osmocote 14–14–14 (3 months) at 0, 35, 70, or 140 g·m2. Plant growth index indicates that plant growth increased significantly at increasing fertilization rates; however, plant overall quality ratings were not significantly different among fertilized plants. Disease incidence in July suggests that late planting may reduce alternaria leaf spot in open-pollinated and hybrid upright type vinca. Disease severity in August was more pronounced on trailing vinca and more severe when plants were not fertilized or fertilized with the highest fertilization rate. Tissue analysis indicates that trailing vinca `Mediterranean Lilac' may require less fertilization than upright type.

scholarly journals Etiology of Alternaria Leaf Spot of Cotton in Southern New Mexico

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1595-1604
Author(s):  
Yi Zhu ◽  
Phillip Lujan ◽  
Srijana Dura ◽  
Robert Steiner ◽  
Jinfa Zhang ◽  
...  
Keyword(s):  
New Mexico ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Severity Index ◽  
Causal Agent ◽  
Universal Primers ◽  
Plasma Membrane Atpase ◽  
Alternaria Leaf Spot ◽  
Atpase Gene ◽  
Cotton Fields

Alternaria leaf spot (caused by Alternaria spp.) is one of the most common foliar diseases of cotton (Gossypium spp.) and occurs in most cotton-growing regions of the world. In surveys of commercial cotton fields, Alternaria leaf spot has increased in prevalence and incidence in southern New Mexico due to favorable environmental conditions in recent years. Incidence, severity, and etiology of leaf spot of cotton in southern New Mexico were determined. Fourteen cotton fields with plants exhibiting leaf spot symptoms were evaluated in October and November 2016, when plants were at late growth stage. Disease incidence was 100% in 13 of the fields, and averaged 70% in the 14th field. Average disease severity index for all fields ranged from 21.5 to 87.0. For identification of the causal agent, 14 isolates (one from each field) were characterized based on morphological features and PCR using universal primers ITS4/ITS5 and primers targeting the plasma membrane ATPase gene. Colonies of all 14 isolates were olive green with distinct white margins and relatively small spores when compared with reference isolates of large-spored species. All 14 isolates were identified as A. alternata. The fungus grew on potato dextrose agar from 5 to 35°C, and optimum growth occurred at temperatures between 20 and 30°C. Cotton plants inoculated with selected isolates of A. alternata displayed symptoms similar to those observed under field conditions. This is the first report of A. alternata as a causal agent of Alternaria leaf spot on cotton in southern New Mexico.

EVALUATION OF NONIONIC SURFACTANTS FOR CONTROL OF CLUBROOT OF CABBAGE USING BAREROOT AND PLUG TRANSPLANTS OF TWO CULTIVARS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 607b-607
Author(s):  
W. Tietjen ◽  
P.J. Nitzsche ◽  
W.P. Cowgill ◽  
M.H. Maletta ◽  
S.A. Johnston
Keyword(s):  
Brassica Oleracea ◽  
Disease Severity ◽  
Nonionic Surfactants ◽  
Plasmodiophora Brassicae ◽  
Severity Index ◽  
Effective Control ◽  
Disease Severity Index

`Market Prize' and `Bravo' cabbage (Brassica oleracea Var. capitata L.), transplanted as peat plug and bareroot plants into a field naturally infested with Plasmodiophora brassicae, Woronin, were treated immediately after planting with a liquid or a granular surfactant. APSA 80™, applied in transplant water, significantly reduced percent clubbing and disease severity index (DSI) compared to control treatments. Miller Soil Surfactant Granular™ did not significantly reduce percent clubbing or DSI. There was a significant effect of cultivar on percent clubbing and DSI. There was no significant effect of transplant type on percent clubbing or DSI. This year's study culminates five years of investigation of surfactants for clubroot control. Specific surfactants have proven to be an effective control of clubroot in cabbage. Chemical names used: nonylphenoxypolyethoxyethanol (APSA 80™); alpha-alkanoic-hydro omega-hydroxy poly (oxyethylene) (Miller Soil Surfactant Granular™).

scholarly journals Epidemiology and management of bacterial leaf spot on watermelon caused byPseudomonas syringae

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1222-1229 ◽  
Author(s):  
E. A. Newberry ◽  
L. Ritchie ◽  
B. Babu ◽  
T. Sanchez ◽  
K. A. Beckham ◽  
...  
Keyword(s):  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Negative Relationship ◽  
Disease Outbreaks ◽  
Field Trials ◽  
Multiple Regression Model ◽  
Bacterial Leaf Spot ◽  
Progress Curve ◽  
Cool Conditions

Bacterial leaf spot of watermelon caused by Pseudomonas syringae has been an emerging disease in the southeastern United States in recent years. Disease outbreaks in Florida were widespread from 2013 to 2014 and resulted in foliar blighting at the early stages of the crop and transplant losses. We conducted a series of field trials at two locations over the course of two years to examine the chemical control options that may be effective in management of this disease, and to investigate the environmental conditions conducive for bacterial leaf spot development. Weekly applications of acibenzolar-S-methyl (ASM) foliar, ASM drip, or copper hydroxide mixed with ethylene bis-dithiocarbamate were effective in reducing the standardized area under the disease progress curve (P < 0.05). Pearson’s correlation test demonstrated a negative relationship between the average weekly temperature and disease severity (–0.77, P = 0.0002). When incorporated into a multiple regression model with the square root transformed average weekly rainfall, these two variables accounted for 71% of the variability observed in the weekly disease severity (P < 0.0001). This information should be considered when choosing the planting date for watermelon seedlings as the cool conditions often encountered early in the spring season are conducive for bacterial leaf spot development.

scholarly journals Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 263-268 ◽  
Author(s):  
S. K. Gremillion ◽  
A. K. Culbreath ◽  
D. W. Gorbet ◽  
B. G. Mullinix ◽  
R. N. Pittman ◽  
...  
Keyword(s):  
United States ◽  
Disease Resistance ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Incidence ◽  
The United States ◽  
Yield Potential ◽  
Cercospora Arachidicola ◽  
Breeding Lines ◽  
Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

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